Praneetha R. Bayyapu Manik Lal Das An Improved and Efficient Micro-payment Scheme. 91-100 2009 4 JTAER 1 http://www.jtaer.com/apr2009/bayyapu_das_p7.pdf db/journals/jtaer/jtaer4.html#BayyapuD09